title: Roles of cilia, fluid flow, and Ca2+ signaling in breaking of left-right symmetry.
abstract: The emergence of left-right (L-R) asymmetry during embryogenesis is a classic problem in developmental biology. It is only since the 1990s, however, that substantial insight into this problem has been achieved by molecular and genetic approaches. Various genes required for L-R asymmetric morphogenesis in vertebrates have now been identified, and many of these genes are required for the formation and motility of cilia. Breaking of L-R symmetry in the mouse embryo occurs in the ventral node, where two types of cilia are present. Whereas centrally located motile cilia generate a leftward fluid flow, peripherally located immotile cilia sense a flow-dependent signal, which is either chemical or mechanical in nature. Although Ca2+ signaling is implicated in flow sensing, the precise mechanism remains unknown. Here we summarize current knowledge of L-R symmetry breaking in vertebrates (focusing on the mouse), with a special emphasis on the roles of cilia, fluid flow, and Ca2+ signaling.
authors.affiliation: Developmental Genetics Group, Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamada-oka, Suita, Osaka 565-0871, Japan. Electronic address: syoshiba@nig.ac.jp.
authors.forename: Satoko
authors.initials: S
authors.lastname: Yoshiba
authors.affiliation: Developmental Genetics Group, Graduate School of Frontier Biosciences, Osaka University, 1-3 Yamada-oka, Suita, Osaka 565-0871, Japan. Electronic address: hamada@fbs.osaka-u.ac.jp.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Hamada
mesh_terms: D000818:Animals; D019521:Body Patterning; D002118:Calcium / Q000378:metabolism; D020013:Calcium Signaling; D016764:Cell Polarity; D002923:Cilia / Q000502:physiology*; D015509:Developmental Biology; D004622:Embryo, Mammalian / Q000502:physiology; D047108:Embryonic Development; D018507:Gene Expression Regulation, Developmental; D008648:Mesoderm / Q000502:physiology; D014714:Vertebrates / Q000196:embryology
chemical_list: D002118:Calcium
keywords: cilia; fluid flow; left–right asymmetry